


Kitten au

by ink_quill_pen



Category: Ao no Exorcist | Blue Exorcist
Genre: Kitten!Rin, Mephisto Pheles is a Little Shit, Mephisto is a cat person?, Rin is a dork
Language: English
Status: Completed
Published: 2020-10-29
Updated: 2020-10-29
Packaged: 2021-03-08 23:54:03
Rating: Not Rated
Warnings: Graphic Depictions Of Violence, Major Character Death
Chapters: 1
Words: 4,015
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/27255259
Author URL: https://archiveofourown.org/users/ink_quill_pen/pseuds/ink_quill_pen
Summary: Rin is a catto and he do a bitetto and Mephisot is there
Relationships: Mephisto Pheles & Okumura Rin & Okumura Yukio
Kudos: 23





	Kitten au

**Author's Note:**

> Just a one shot bc why not. I started this a while back and just kinda forgot about it

Yukio stood looking over the grave, to think he was the last one. “So I guess this means I won,” Yukio laughed softly reading the words carved into the mossy stone. 

Here lies Rin Okumura, the hero who sacrificed his life for a better world.

“You lied to Shura, you didn’t even make it to the rank of arch knight, but you killed Satan... Everyone loves you now that you are gone,” Yukio scoffed at the stone. “Lucifer and Mephisto are finally getting along. Neither of them is going to let me die, I can feel it. Egyn injected me with the serum while I was asleep. I guess I will never get to see you again, will I?” 

“Why did you let me win Rin? You were supposed to leave first!” The twin snapped, his eyes filling with fury as he glared at the name. That cursed name, his brother would always be better than he wouldn’t he?

~~~~~~~~~~~~~~~~~

A soft white cat strode across Mephisto’s desk. Not being careful of any of the papers strewn across the ordinance carved desk. Meowing happily the cat gave no care to the demon’s work, who at this point was irritated at the cat's antics. 

“Rin, get off my desk,” Mephisto growled trying to sort his fallen papers. 

Rin mewed in pure defiance as he sat in the middle of the desk, only irritating the demon king further. “Rin you have a bed right over there,” Mephisto growled pointing to the pink pillow tucked into the corner of the room. 

It was comfortable and it made the kitten feel safe, but Rin wanted to be with Mephisto, the demon had forgotten to give him attention, a deadly offense for any cat owner. Rin mewed once more, extending his claws and he batted for Mephisto’s hand.

He wanted scratches but Mephisto was too busy with his work, it was brutally unfair. “Rin if you scratch my desk I will not hesitate to punish you,” Mephisto growled in warning, making the kitten flinch.

His angry tone ruined Rin’s mood, well Rin didn’t want attention from him anymore. Mephisto was going to regret his words and actions. Rin hopped off the desk and walked over to the bed, he could feel Samael’s glare leave him as the demon got back to his work. Rin had his back turned to the demon king as he laid on the plush pillow. He was too upset to even look at Mephisto.

Thankfully he was able to drift off to sleep, avoiding hours of excruciating waiting. Rin napped softly giving mephisto to think over his actions, Rin only wanted attention, after all, it was on him for not spending time with Rin. Besides, taking breaks could help him be more productive in his work. Rin was being a pest but a helpful pest.

He got through the rest of his work looking forward to the reward of cuddling with the small kitten he called his own. When he was nice Rin was the cuddliest being of them all, he loved all the pets, head scratches, belly rub, and cuddles. 

His pen fell to the desk clicking softly as it collided with the wood. “Oh Rin,” Mephisto purred happily, turning his chair to the kitten who was napping peacefully, well he was until Samael decided to bother him.

“Rin, it is time to wake up,” Mephisto stood softly and walked over to the pillow.

Rin groaned angrily in warning to Mephisto as he got too close to the cat. He was still mad at the time king for his actions, Rin had quickly learned how to hold onto a grudge during his time with Samael. 

“Rin, don’t be fussy,” Mephisto growled in warning as he kneeled on the ground, reaching for Rin. 

The kitten in response snarled, though it appeared to sound like more of a hiss. 

“Rin,” Mephisto snarled, making the kitten whimper in response. Samael had been mean to him and he wasn’t making it up. He was just trying to ignore it, Rin wasn’t having it.

“Rin I am sorry for pushing you away but you are my cat so I should get to hold you!” Mephisto pouted.

“Noo,” Rin hissed demonically like the demonic beast he truly was.

“You are being unnecessarily mean !” Mephisto huffed.

The door flew open and Amiamon walked in.

“Are you talking to that cat again?” Amaimon whined walking into the room.

“Yes,” Mephisto bit in response, huffing as he sat back down at his desk. “Now what do you want?”

“It has been too long since you gave me any attention,” Amaimon huffed.

“You don’t need my attention,”

“And neither does that thing,”

“That thing has a name Amaimon, and if you can’t be respectful then feel free to leave,”

The response seemed to hit the wrong way and Amiamon soon grew furious, “Why do you act like that thing is above me? It is a mere animal, no higher than a rat, just another prey item, and on top of that you name it after the excuse for a demon!”

“You have overstayed your welcome Amaimon,” Mephisto snapped, the demon eyes shifted from one of a reasonable mind to a more feral, and eldritch tone. The pulp split and his eyes began to glow a sickly green with yellow bleeding through the iris. the said demon soon did take his leave, though he wasn’t overly joyous about the situation. 

Rin sat silently on his bed, gazing over to Mephisto to see how he handled it all. The demon king stalked over to his desk and sat down, Rin sensing the tension from his ”owner,” crawled over to the demon and began to provide small licks for comfort.

The soft acts of affection were enough to elicit purrs from the demon king. The electric gaze from Samael fell upon the cat. “You truly are a little darling, even if you are a pain most of the time,”

A soft mew of content was all Mephistopheles got in response as the kitten continued to soothe his caretaker.

“So does this mean you will let me pet you?” Samael purred, moving hands around the small frame of the lesser animal and setting the ball of fluff onto his own lap.

Rin didn’t fight the affection and instead happily welcomed it. Even providing small purrs for the king to delight in.

“ see being a good kitty isn’t hard,”

“ Sometimes,” Rin mewed contently as he lavished in the attention.

“Sometimes?” Mephisto cooed in curiosity.

“Getting pushed into a bathtub sized hot tub isn’t what I would refer to as fun,” Rin hissed in response.

“You were taking far too long to get in the water, besides you like water if I recall correctly,” Mephisto snickered as he recalled the sight of the panic kitten as it ran around the bathroom losing traction as it tried to be rid of water.

“It was still rather mean on your behalf, if it was anyone else I would have left scars on their unprotected bodies. But knowing you that would somehow only be worse for me.”

“You see me as such a villain Rin, I think that is a bit unfair on your behalf,”

“Is it really?” Rin mewed.

“Yes!”

“Whatever I am going to be in my room if you need me,” Rin mewed standing from his position and moving towards the door which was slightly ajar from when Amaimon had entered so abruptly earlier.

The walk wasn’t overly tedious as Rin did enjoy the stretch his legs got as he had been sleeping for most of the day. Mephistos mansion was full of empty unused rooms, rooms with no purpose, and simply odd rooms that didn’t even seem to fix with the rest of the mansion.

Rin nuzzled against the walk pressing his light fur against the hard surface as he got the sudden urge for an embrace. Being a cat came with a certain list of disadvantages, 1 being so small was a challenge of its own, 2 everyone wants to touch you, 3 sudden and odd urges, 4 having to deal with Mephisto. All of the options were challenges of their own, Simply bothersome with easy and simple workarounds. Number 4 however was by far the most difficult challenge.

Mephisto was a pest on his own caliber, sometimes he was manageable other times he was unbearable, Rin couldn’t figure out what the damn king wanted half the time… Well, he had an entirety to figure that out, who Mephisto truly was.

Rin moved on from the wall and continued his walk down the hall. Rin slipped through the door and jumped onto the cat based furniture scattered across the room, his room to be more exact. 

This was the cat room in the mansion, the room where Rin could roam and linger freely from the threat of Mephisto, and to accompany that freedom part of the wall was made of glass so Rin could watch the garden and see the rainfall…

It had been years since Rin was last out in the rain, it always seemed to make his fur matted and tangled, a bother to get untangled, and on top of that, he despised how the cold water felt across his fur.

Rin jumped onto his tower and clawed his way up to the very top where a light blue pillow was placed for his comfort, Rin melted into the pillow as he lay down. 

Thankfully the top had small walls surrounding the edges to prevent Rin from falling off in his sleep. The cat body was far more fragile than his human one, so he had to be careful when it came to sleeping in high places.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The cracking thunder awoke the napping kitty, who was content in his room. The room was dark, too dark, no light was present, and only the occasional flash of lightning provided light.

Of course, being a cat he was more adapted to seeing in the dark, but he still didn’t like it, especially at the size he was… RIn hoped down step by step from his tower and slowly stalked his way over to the small button panel that was installed in the room.

The buttons would be the answer to all his problems, he would call Belial and then he would be safe. No buttons held light as Rin approached them, reality struck as Rin felt this heart sink, dropping down to his small paws. 

Rin could barely stand as his legs began to quiver. RIn was going to have to leave the room, when it was dark out, during a storm….

Rin began to mew in panic, crying out for any of the servants who may be passing by. Each new wave of thunder seemed to rivet through Rin as the lighting crawled closer to the mansion.

The cat’s fur rose on his back as he felt the next bolt of lightning form, it was far too close for comfort, he had to get away, and now.

Scampering over to the door Rin scratched and clawed at the door trying to break through the wooden surface, he had to escape and now! 

The charge would be far too much for his small body to handle, he would die!

The lightning struck, sending the thundered tearing through the house, and ripping through the ears of the feline.

“Mephisto!” Rin mewled in desperation, terror infused with his voice. He heaved as he continued to escape from the prison, the lighting was coming for him! He was going to be killed!

The door swung open as Rin shook in fear, cowering on the floor. A pair of gloved hands embraced him and scoped the small frame up into a warm embrace. 

“Master I found him!” Belail said, walking into the darkened hallway, only the subtle glow of a candlelit the halls as the butler walked through. Soon, however, another candlelight appeared amidst the darkness.

“He must have gotten trapped once the power went out,” Mephisto sighed softly, safely transferring the kitten into his own arms. “Thank you, Belial for finding him,”

“Of course my lord,” With the short reply the butler has sauntered off, getting lost in the darkness once again.

The furred animal snuggled into Mephisto’s coat, shivering as the aftermath of the adrenaline ran through him. Rin’s mind raced back to the very night he had taken this form, the storm was furious at him, he could only run away and take cover under various trees and benches. 

Rin only was safe when he arrived at Shiro's gravestone, no lighting dared to attack him there. RIn could only remember the cold feeling as the rain poured over him, he knew at the very moment he would never have the life he once had…

The deal he had made with Mephisto truly did change everything, who would have known when Mephisto said he wanted Rin by his side forever he meant in a cat form? Who could have guessed fighting Satan would mean losing his own life as well…

Probably Mephisto, the cruel bastard planned all of it.

“It’s alright Rin, I will protect you remember? You are safe,” Mephisto cooed to the small cat.

Rin purred in response instead of acknowledging the comfort the words gave him… He was safe, Mephisto would keep him safe. The walk to Mephisto’s room was short though Rin could not say he mined the short wait time, as he knew what awaited him next.

The cat was placed on the bed and Mephisto soon began to dress down, taking off his coat, his hat, his vest, for the rest of the clothes he had some dignity and changed into the robe with only a door providing protection for the feline’s eyes and sanity.

The demon came out dressed in a simple silk robe, and he slid happily in bed. Giving Rin the opportunity to crawl his way over to the king and lay in his lap, awaiting the pampering he knew was coming.

“Well it appears someone is benign rather needy,” Mephisto scoffed at the sight of the dazed expression plastered on the cats’ face. “Very well then, I suppose since you are being so lovely I will provide you with what you desire,”

The cat quickly turned to a liquid as mephisto slid his hands over the silk fur. Rin was quick to begin purring as the pampering began, first petting, then getting his fur brush out, then more petting, and maybe an occasional play. 

Mephisto was more than happy to provide the cat with affection, he had nothing better to do after all. All his gaming consoles were down, and he did not wish to do paperwork by candlelight.

“Well look who is being all sweet now?” Mephisto teased the feline softly, poking the pink nose of the cat.

Rin murmured in reposed as he recoiled back and stared at the finger in confusion. The cat had wishes to be booped, especially when he was just benign pampered. The purrs stopped as he continued to stare in confusion. Had Mephisto though pestering him was a good idea?

Had the time king forgotten what Rin was capable of?

Rin hissed at the finger, surprising the king. 

“Rin why are you being so fussy?” Mephisto growled in response. “You were being so cute for once,” 

Rin continued his fit as he stood from the lap and slowly began to back away, managing to fall off the bed and land on his small furred belly. The small collision was enough to get the cat’s mind off the unwanted boop and on the pain riveting through him.

“Did you just hurt yourself?” Mephisto scoffed.

“Help,” Rin whined from the floor.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The next morning Mephisto slept soundly with the kitten once again positioned on his chest. Light peered in from the corner of the room, giving the area a spacious, airy feeling. The small white creature’s fur seemingly glistened in the light making the feral beast almost angelic looking.

Rin awoke first, ear flickered softly as he looked around his room. The small pink nose of the cat wiggled softly as he sniffed his surroundings. A new smell was present in the room. The aroma had hints of pine, mint, and rain? It was an odd smell but comforting and pleasant. 

The house of the scent however did not share the same peace of mind as Rin did. Amaimon caught the cat by his scruff and threw the feline against the wall. The small body abruptly collided with the wall, a sickening crunch resulted.

Rin could only spare a small yowl of pain as he felt his soul slipping away. 

“Rin?” Mephisto questioned softly waking up. As his vision fixated on the scene Mephisot flew into a rage.

Amaimon was soon pinned to the ground by the elder king’s magic. Mephisto slid out of his bed and walked over to the broken cat. Wrapping His hands around the body Mephisto picked Rin up, looking over the feline’s body for any trace of injury…

Then Rin’s breathing stopped as he lay limp in Mephisto's arms

“You killed him, Amaimon. Do you understand what you just did?! Now I have to go find another white cat, and then register it and pay for it! Then I have to get the kitten trained again,” Mephisto barked holding the small body close to his chest.

“Why do you even want that thing can't you see it’s just a waste of time,” Amaimon growled back.

“I can see that I can no longer trust you with free roman of my mansion, and I certainly can’t trust you with my possessions,” Mephisto snarled, but soon his mood lightened as an idea crawled into his mind. “Since you destroyed my precious darling you will be his replacement till I find a suitable kitten to take in,”

~~~~~~~~~~  
A month or two later  
~~~~~~~

Mephisto sat on the floor of his room, the timeless body of the cat stayed still, so very still. Thankfully he had been able to preserve it probably so rot did not set in. The body lay in the middle of what almost appeared to be a summoning circle and with a drop of his blood, the circle began to emanate light.

The body lit up in flames and slowly turned to nothing but ash

.

..

…

Slowly the pile of ash began to shift softly. A soft mew came from the pile as a kitten began to take form out of the ashes. Rin’s soul which had originally been locked away was now inhabiting the small body.

Rin stood using the small wobbly legs that had been made, the white fur was now drenched in ash, making the kitten look grey. Rin appeared to be no older than three weeks and as young as one week. The small body of the kit was very unstable and Rin quickly found out that walking would be a challenge in this form.

“Welcome back Rin,” Mephisto soothed, picking up the small kitten. 

“Hi,” Rin meowed back, his voice only being more warped by the small body and sounding higher and cuter than before.

“I think you got cuter since last time,” Mephisto hummed. “I think I know the perfect addition to you. But first, you need a bath,”

“Why,” Rin whined in response.

“You are covered in ash and smell like smoke, and I don’t want to deal with a smoky kitten,”

“I can clean myself, I don’t need a bath,” Rin hissed in defiance.

“Yes you do,” Mephisto purred, petting the kitten as he stood. “Belial, prepare a bath for our kitten, and if I don’t return when it is ready, wash him,” Mephisto ordered the butler handing the smoky furred feline to him.

The demon king then walked off leaving the two alone. Rin did not fight the butler as he preferred baths from the servant. Belial was always careful and gentle with him, taking the time he needed to wash the kitten instead of being impatient and trying to rush the process. 

After a proper bathing RIn lay happily on the countertop as his fur was softly dried. The silk fur clung to his small body showing how tiny the kitten truly was. Mephisto then walked into the room holding a silky blue ribbon. 

Rin didn’t resist the ribbon benign tied around his neck, it wasn’t choking him nor was it too loose, it fit nicely and left enough excess for Mephisto to tie a bow on the back. It was a bit annoying but Rin knew there was little he could do to stop it.

~~~~~  
Blood and gore warning  
~~~~

The Kitten now being able to walk, scurry down the halls, inspecting all the changes that occurred to his home while he was “away”. A soft squeak caught his attention and a green hamster ran over to him, the small rodent sat down right in front of the kit, staring up at the predator. The red eyes of the hamster caught the attention of the feline. Rin’s head tilted to the side as he mewed in question.

Rin sat down where he stood and he leaned towards the hamster, sniffing the rodent softly.

A squeal echoed through the halls as Rin’s fangs latched on to the small rodent.

Rin’s fangs did not pierce the skin of the rodent but instead held the animal softly in his mouth. 

The kitten stood and began to hop softly to Mephisto’s office, only to be bitten as he carried the rodent.

Recoiling from the pain Rin dropped the rodent and hissed at his attacker. 

The hamster hissed back and scampered away. The pure pride of the hamster was enough to infuriate the cat enough to track the hamster again. 

This time, however, instead of gentle hold he readied his fangs to kill.

Pouncing into the air he flung himself onto the rodent and drove his fangs into the small animal, getting a scream from the green blob in response.

Amaimon tried his best to squirm out of the cat's grasp, failing and biting aimlessly at the Kitten cheek. 

Rin yowled as he felt further pain slide down his face.

Extending his claws Rin tore open the hamster as he threw it onto the floor, splattering his freshly cleaned coat with blood. 

The hamster laid dead, beaten, torn, and bloodied as Rin picked it up once again. 

This time the kitten did not bounce as the counter-attack had put him in a rather foul mood but he still he needed to present his catch to his owner.

To show the demon king that he too thought of this domain as his and expected to stay.

Rin crawled his way into the office and walked past the visitor sitting across from mephisto. Rin jumped onto the desk and places the bleeding hamster right on top of Mephisto’s papers for the demon king to see.

Mephisto abruptly stopped the conversation he indulged in and looked at the kitten who proudly admired his catch as he waited for approval.

The king was tied between pride, joy, and disgust as he viewed the creature… Amaimon had overstepped his bounds, hadn’t he? One could suppose it was Mephisto’s fault for not warning the other king of the kitten he had resurrected, but how was he supposed to know the two of them would run in so soon?

“Well, I don’t think I could give you a better introduction to my cat,” Mephisto sighed looking at the cat. “I named his after your later brother, I have found they share very similar characteristics, most importantly being unbearable and a pain,”

The small introduction caught Rin’s attention as he looked over to Yukio. The kit mewed softly as he walked over to his brother. Yukio hesitantly reached his hand out to pet the kit. Rin connected the embrace and pushed himself against Yukio’s hand, purring softly as he was codled.

“I guess they do seem similar,” Yukio chuckled softly gazing down at the cat.

The end


End file.
